In a communication network from wide area communication such as public lines and medium-scale area communication such as a company premise local area network (LAN) down to short-distance communication connecting user terminals in an office room, a meeting room, and the like, packet communication based on the Internet Protocol (IP) is advanced and application thereof is expanded in all areas. Media transmitting an IP packet are substantially converging to Ethernet (registered trademark) for wire communication, and are substantially converging to a third generation (3G)/Long Term Evolution (LTE) system for long-distance wireless communication and to The Institute of Electrical and Electronics Engineers, Inc (IEEE) 802.11 wireless local area network (LAN) system, which is known as a nickname of Wireless Fidelity (Wi-Fi) for middle-distance and short-distance wireless communication.
The concept called a software defined network (SDN) has been gaining attention in recent years. The SDN literally means that operation of network is defined with software description, and includes, as major technical components receiving the most attention, virtualization of a network, and Open Flow Switching that is one of the methods and protocols for controlling the virtual communication and is open specifications independent of a vendor.
Open Flow (registered trademark) is a technique for defining communication as an end-to-end flow and performing path control, load distribution, optimization, and the like for each flow, and standardization of which has been promoted by a nonprofit organization called Open Networking Foundation (ONF). Specifically, relay apparatuses such as a switching hub (switch) of a data communication path do not analyze and forward each data packet in an autonomous distributed manner, but an apparatus called a controller centrally controls the relay apparatuses.
Open Flow separates a control plane serving as a part for analyzing data, determining a forwarding destination, and controlling determination controlling from a data plane simply serving as a part for physically forwarding a packet. An Open flow controller (OFC) responsible for the former instructs a forwarding rule, and an Open Flow switch (OFS) responsible for the latter performs forwarding based on an instruction of the OFC, specifically, on a flow table of the OFS to which the OFC makes an addition and performs rewrite. This mechanism is used to utilize Open Flow as a tool for controlling the network virtualization.
SDN related techniques such as network virtualization and Open Flow are increasingly utilized in Web/cloud data centers on which communication loads concentrate among IP communication networks, a communication carrier backbone and the like, and flexible optimization control achieves efficiency of communication traffic, reduction in the number of network apparatuses and the like, and reduction in cost and energy and the like. Such a technique called Open Flow has been already known.
Patent Literature 1 discloses a communication method and the like where high-order protocol information is included in a Transmission Control Protocol (TCP) header for the purpose of improving conformability of a computer system and providing a computer system capable of performing flow control corresponding to a higher-order protocol than that of a TCP layer.